Apparatus for measuring electro



Dec. 22, 1953 3, w, GRAHAM 2,663,842

APPARATUS FOR MEASURING ELECTROSTATIC CHARGES Filed Oct. 7, 1952 o 9 n j I Lk a: L ,J' k fif Q m I\ y: lNVENTOR GEORGE MGRAHAN BY flaw-1 77/13;

AGENT l atentecl Dec. 22, 1953 APPARATUS FOR MEASURING ELECTRO- STATIC CHARGES George W. Graham, Beloeil, Quebec, Canada, assigner to Canadian Industries Limited, Montreal, Quebec, Canada, a corporation of Canada Application October 7, 1952, Serial No. 313,575

1 Claim.

This invention relates to an apparatus for measuring the charges of static electricity accumulated upon the surfaces of fibers, filaments and yarns.

Numerous fibers, filaments and yarns made of synthetic or naturally occurring material show a strong tendency to accumulate charges of static electricity either during the production thereof, during their subsequent treatment or the subsequent treatment of articles made therefrom in connection with the usual finishing operations, or in the course of the use of such articles. Many agents have heretofore been proposed which will prevent or reduce the accumulation of an electrostc tic charge upon the surfaces of such fibers, filaments and yarns. It follows that before an anti-static agent is propounded for use with certain fibers, filaments and yarns, it must be tested for eificiency under the various conditions to which the fibers, filaments and yarns will be exposed, and it is extremel important that accurate means be provided to determine with certainty the electrostatic charge of the treated fibers, filaments and yarns under each one of those conditions. Furthermore, it is of advantage to determine if a certain fiber, filament or yarn requires the application of an anti-static agent.

This invention has as its object the provision of an apparatus for measuring with accuracy the charges of static electricity accumulated upon the surfaces of fibers, filaments and yarns.

The apparatus of this invention comprises in combination an L-shaped support, a motordriven eccentric placed on the bottom part of said support, a filament of non-conductive material having one end attached to said eccentric and the other end attached to a hook of non-conductive material adapted to engage one end of a hank of the filaments, fibers and yarns to be tested for static electricity, a second filament of non-conductive material passing over two pulleys attached to opposite sides of said support at the top thereof, said second filament having one end attached to a balance weight and the other end attached to a second hook of non-conductive material adapted to engage the other end of said hank, and three metallic rods attached to said support at a point intermediate between said hooks and adapted to come into contact with said hank transversely thereof, two of said rods being made of steel and being connected to the ground and having pins mounted thereon to guide the motion or" said hank, the other rod being made of brass and being positioned between said steel rods and being attached to said support by non-conductive means and being connected to a voltage measuring device.

The apparatus will be better understood by reference to the accompanying drawing wherein Figure 1 is a front elevation of the apparatus, and

Figure 2 is a section on the line 2-2 of Figure 1.

Referring to the drawing, an eccentric l driven by a motor 2 is placed on the bottom part of an L-shaped support 3. Attached to the eccentric l is a filament 4 of non-conductive material, such as nylon, having its other end attached to a hook 5, which engages one end of a hank of filaments 6. The L-shaped support 3 has two pulleys l attached to opposite sides at the top thereof. A second filament 8 of non-conductive material passes over the pulleys l and has one end attached to a balance weight 8 and the other end attached to a hook H] which engages the other end of the hank 6. Attached to the L-shaped support 3 at a point intermediate between the hooks 5 and in are three metallic rods H and I2 contacting the hank 5 transversely thereof. Two of the rods, designated b II, are made of steel and are connected to the ground as at 13. The third rod 12 is made of brass and is positioned between the steel rods H and is attached to the support 3 by non-conductive means 14. The steel rods II have pins is mounted thereon to guide the motion of the hank 6. The brass rod 12 is connected to a voltage measuring device comprising a modulator IS, a shield ll, an audio amplifier l8, a microammeter l9, and an electric fan 20.

The function of the apparatus is as follows. Static electricity is generated by rubbing the hank of filaments 6 on the brass rod I2. The rubbing action is produced by the eccentric l driven by the motor 2, which is preferably a R. P. M. motor, and it is translated to the hank 5 through the filament 4 and hook 5. lhe tension is maintained on the hank S by the weight 9 connected to the other end of the hank 5 by means of the filament 8 and hook it. The charge generated by the filaments on the brass rod i2 is conducted to one electrode of the modulator It. This induces a charge of electrostatic induction on the second electrode of the modulator. The blades of the motor-driven fan 25 interrupt the field passing between the electrodes of the modulator i6 and cause an alternating voltage to appear on the second electrode. This is amplified by the audio amplifier IS, the output of which actuates the meter [9. The meter reading is thus proportioned to the charge developed on the brass rod.

In order to reduce the rate of voltage built up,

a condenser such as a 0.001 mf. condenser is preferaloly connected between the brass rod l2 and ground, as at 2!.

Higher and more consistent voltages result from the use of the brass rod i2 than from the use of a steel rod in lieu thereof. The static generation depends on the difference between the brass rodhank of filaments and the steel rods-hank of filaments contact potentials. This difference in potential is larger and more definite with a central brass rod than the difference between a central steel rodhank of filaments potential and grounded steel rods-hank of filaments potential. The grounded steel rods restore the hank of filaments to a basic electrical state after each rub over the central brass rod.

It will be readily understood that many modi-= fications of the above described apparatus may be made without departing from the spirit of the invention and hence fall within the meaning and scope of the appended claim.

Having thus described my invention, What I claim is:

An apparatus for measuring the charges of static electricity accumulated upon the surfaces of fibers, filaments and yarns comprising in combination an L-shaped support, a motor-driven eccentric placed on the bottom of said support, a non-conductive filament having one end ataecaeae tached to said eccentric and the other end attached to a non-conductive hook adapted to engage one end of a hank of said fibers, filaments and yarns, a second non-conductive filament passing over two pulleys attached to opposite sides of said support at the top thereof, said second filament having one end attached to a balance weight and the other end attached to a second non-ccnductive hook adapted to engage the other end of said hank, and three metallic rods attached to said support at a point inter mediate between said hooks and adapted to come into contact with said hank transversely thereof, two of said rods being made of steel and being connected to the ground and having pins mounted thereon to guide the motion of said hank, the other rod being made of brass and being positioned between said steel rods and being attached to said support by non-conductive means and being connected to a voltage measuring device. GEORGE W. GRAHAM.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,189,352. Siegenheim -l Feb. 6, 1940 2,421,430 Ott June 3, 1947 2,532,010 Ccurvoisier Nov. 28, 1950 

